1. Field of Invention
The present invention relates to a converter. More particularly, the present invention relates to a converter, which reduces the voltage between any two nodes.
2. Description of Related Art
The technology of wireless power transmission is applied in many fields recently, for example, electric vehicle, consumer electronic device, etc. The technology of wireless power transmission transmits power by using a theory of electromagnetic induction.
Referring to FIG. 1, FIG. 1 is a schematic diagram of a known converter. As shown in FIG. 1, the known converter 100 includes a voltage transformer 120, a full bridge inverter circuit 140, a primary side compensation capacitor Cp and a secondary side compensation capacitor Cs. The voltage transformer 120 is formed by coupling the primary side inductor L1 and the secondary side inductor L2, in which a mutual inductance between these inductors is M. The full bridge inverter circuit 140 includes switches S1˜S4 and the bridge rectifier 160 includes diodes D1˜D4. The full bridge inverter circuit 140 transforms an input DC voltage Vin into an AC voltage and transmits it to the voltage transformer 120. Then, the AC voltage is transmitted to the bridge rectifier 160 through the primary side inductor L1 and the secondary side inductor L2, and the output DC voltage VDC,out is generated. Furthermore, because air gaps generally existed between the primary side inductor L1 and the secondary side inductor L2, the leakage inductance is relatively large. As a result, the output voltage of the voltage transformer 120 is reduced. Therefore, the known converter 100 generally includes the primary side compensation capacitor Cp and the secondary side compensation capacitor Cs to compensate the leakage inductance of the voltage transformer.
In the prior art, when the known converter 100 is operated in a high output power, the current of the primary side and the secondary side are increased with the output power. Accordingly, the voltage of the nodes of the primary/secondary inductors L1/L2 is significantly increased, and the voltage of the primary/secondary side compensation capacitors Cp/Cs is relatively high. Thus, in order to enhance the operation safety, it is necessary to select inductors and capacitors with high voltage withstanding ability, and thus the cost of the converter is increased.
Therefore, it is a major development target to efficiently reduce the voltage of the nodes in a converter in the situation of high output power.